The plague quarantine island home to the alleged "Vampire of Venice."

The final resting place of New England's last "vampire."

A sacred mountaintop temple offers a fine cup of tea to visitors who can survive the journey.

The second-longest continuous wall on the planet protects a hidden secret in the deserts of India.

An Aztec temple, the largest man-made pyramid in the world, sits buried in earth with a Spanish church set on top.

The central mosque of this Mali town is entirely built from mud.

Neither Spanish settlers nor anyone since has been able to tell who built these strange California rock walls.

The largest prehistoric ruins south of the Sahara, once a powerful center of international trade.

Over 4,700 miles of trees being planted to hold back the desert.

Thanks to the building of a life-giving reservoir, part of the Great Wall of China is now a dive site.

This imposing memorial contains the remains of Che Guevara — and 29 other guerrillas who died with him in Bolivia.

Hidden just under the waters around this Turkish island are the ruins of a once great city.

This stately 19th century library pushed architectural boundaries at a time when the public library movement was just taking off.

"Call for the doctor, call for the nurse... Vote!! said the lady with the alligator purse."

Parking garage where Bob Woodward met Watergate source "Deep Throat."

Soldiers were buried next to Lee's house in the center of Arlington Cemetery to dissuade the general from reclaiming his property after the war.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

California's own medieval Italian castle, authentic down to the 300-year-old iron maiden in the dungeon.

This historic California cemetery holds the bodies of veterans of both the Civil War and the Donner Party.

There just so happens to be a court even higher than the U.S Supreme Court: a basketball court in the building itself.

Where beautiful signs live on forever.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

Ancient rock-hewn town that witnessed key events of Georgian history.

A city built from mud and known as the "Manhattan of the desert."